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<h2><a name="SECTION0025310000000000000000"></a><a name="minimal-example"></a>
<br>
23.3.1 Basic example 
</h2>

<p>
The <tt class="module">unittest</tt> module provides a rich set of tools for
constructing and running tests.  This section demonstrates that a
small subset of the tools suffice to meet the needs of most users.

<p>
Here is a short script to test three functions from the
<tt class="module"><a href="module-random.html">random</a></tt> module:

<p>
<div class="verbatim"><pre>
import random
import unittest

class TestSequenceFunctions(unittest.TestCase):
    
    def setUp(self):
        self.seq = range(10)

    def testshuffle(self):
        # make sure the shuffled sequence does not lose any elements
        random.shuffle(self.seq)
        self.seq.sort()
        self.assertEqual(self.seq, range(10))

    def testchoice(self):
        element = random.choice(self.seq)
        self.assert_(element in self.seq)

    def testsample(self):
        self.assertRaises(ValueError, random.sample, self.seq, 20)
        for element in random.sample(self.seq, 5):
            self.assert_(element in self.seq)

if __name__ == '__main__':
    unittest.main()
</pre></div>

<p>
A testcase is created by subclassing <tt class="class">unittest.TestCase</tt>.
The three individual tests are defined with methods whose names start with
the letters "<tt class="samp">test</tt>".  This naming convention informs the test runner
about which methods represent tests.

<p>
The crux of each test is a call to <tt class="method">assertEqual()</tt> to
check for an expected result; <tt class="method">assert_()</tt> to verify a condition;
or <tt class="method">assertRaises()</tt> to verify that an expected exception gets
raised.  These methods are used instead of the <tt class="keyword">assert</tt> statement
so the test runner can accumulate all test results and produce a report.

<p>
When a <tt class="method">setUp()</tt> method is defined, the test runner will run that
method prior to each test.  Likewise, if a <tt class="method">tearDown()</tt> method is
defined, the test runner will invoke that method after each test.  In the
example, <tt class="method">setUp()</tt> was used to create a fresh sequence for each test.

<p>
The final block shows a simple way to run the tests.
<tt class="function">unittest.main()</tt> provides a command line interface to the
test script.  When run from the command line, the above script
produces an output that looks like this:

<p>
<div class="verbatim"><pre>
...
----------------------------------------------------------------------
Ran 3 tests in 0.000s

OK
</pre></div>

<p>
Instead of <tt class="function">unittest.main()</tt>, there are other ways to run the tests
with a finer level of control, less terse output, and no requirement to be
run from the command line.  For example, the last two lines may be replaced
with:

<p>
<div class="verbatim"><pre>
suite = unittest.TestLoader().loadTestsFromTestCase(TestSequenceFunctions)
unittest.TextTestRunner(verbosity=2).run(suite)
</pre></div>

<p>
Running the revised script from the interpreter or another script
produces the following output:

<p>
<div class="verbatim"><pre>
testchoice (__main__.TestSequenceFunctions) ... ok
testsample (__main__.TestSequenceFunctions) ... ok
testshuffle (__main__.TestSequenceFunctions) ... ok

----------------------------------------------------------------------
Ran 3 tests in 0.110s

OK
</pre></div>

<p>
The above examples show the most commonly used <tt class="module">unittest</tt> features
which are sufficient to meet many everyday testing needs.  The remainder
of the documentation explores the full feature set from first principles.

<p>

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<span class="release-info">Release 2.5.1, documentation updated on 18th April, 2007.</span>
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